Automobile Catalysts Research Articles

용융기술(熔融技術)을 이용(利用)한 자동차폐촉매(自動車廢觸媒)에서의 백금족(白金族) 금속(金屬) 회수(回收) 연구(硏究)

자동차 폐촉매로부터 폐촉매 중에 함유되어 있는 백금족 금속(Pt, Rh, Pd)를 회수하는 방법으로는 크게 건식법과 습식법이 현재 이용되고 있다. 본 연구에서는 건식 용융법으로 폐촉매로부터 백금족 금속 회수하기 위한 기초 실험으로 포집금속으로 Fe와 Cu을 사용하여 폐촉매를 용융하였을 때 각각의 농도 변화를 비교함으로써 용융 조건과 적정 포집금속으로 찾는 것을 목적으로 하였다. 본 실험으로 얻어진 결과를 요약하면 Fe을 포집금속으로 히는 것이 Cu을 포집금속으로 사용하는 것보다 회수율 측면에서 유리하였으며, 용융 처리 온도는 <TEX>$1,500^{\circ}C$</TEX>에 비교하여 <TEX>$1,600^{\circ}C$</TEX> 용융 하였을 때 슬래그 중 잔류하는 백금족 금속의 농도 변화율이 크게 향상되었다. 용융 온도 <TEX>$1,600^{\circ}C$</TEX>의 경우 처리 후 슬래그 중 백금족 원소인 Rh, Pd, Pt의 평균 농도는 각각 6.21 ppm, 5.98 ppm, 6.97ppm으로, 이는 용융 온도 <TEX>$1,500^{\circ}C$</TEX>시 보다도 슬래그 백금족 원소 중 Rh와 Pd는 농도변화율 측면에서 각각 50.58%, 55.31%향상되었다. 그러나 폐촉매 중의 Pt의 초기농도가 12.9 ppm으로 낮아 용융처리 후 농도변화율의 비교가 어려웠다. The dry method and wet method are currently used for the recovery of platinum group metals (Pt, Rh, Pd) contained in spent automobile catalysts. The study herein aims to identify the melting condition and optimum collector metal in accordance with a comparison of each concentration change in melting waste catalysts, using Fe and Cu in a basic experiment to recover waste catalysts through application of the dry melting method. As a summarized result of the experiment herein, it was determined to be more advantageous to use Fe as a parent material rather than Cu from the aspect of recollection rate, and the concentration change rate of platinum group metals within slag was greatly enhanced at <TEX>$1,600^{\circ}C$</TEX> melting condition rather than at <TEX>$1,500^{\circ}C$</TEX> in terms of melting processing temperature. The mean concentration of platinum group metals - Rh, Pd and Pt - within slag after a melting process at <TEX>$1,600^{\circ}C$</TEX> were 6.21 ppm, 5.98 ppm and 6.97 ppm. The Rh and Pd were 50.58% and 55.31% respectively greater than the concentration change rate of platinum group metals in slag at a melting temperature of <TEX>$1,500^{\circ}C$</TEX>. However, since the initial concentration of Pt within the waste catalysts was 12.9 ppm, is relatively low, it was difficult to compare concentration change rates after the melting process.

An efficient hydrogenation of various alkenes using scrap automobile catalyst

An efficient, easy, cheap, convenient, and safe procedure for the reduction of various alkenes to the corresponding alkanes is developed by using scrap automobile catalyst as an efficient hydrogenation catalyst. This procedure not only gives high yields, but also allows recycling of automobile wastes as a catalyst in organic reactions and is representative of green chemistry.

Topics Related to Surface Science in Automobile Industry

Several R & D topics related to surface science in automobile industry are reviewed in chronological order from early 1970s, including topics on instrumental analysis of surfaces, sputtering and plasma processing, birefringent thin films, all optical sensors, transient analyses of surface chemical reactions in automobile catalysts, recordable CD-Rs which can be played in DVD-ROM drives, solar cells and photochemical reduction of CO2.

Cycling of rare earth elements in the atmosphere in central Tokyo

Concentrations of 14 rare earth elements (REEs) in six size classes of airborne particulate matter (APM) (<0.43, 0.43-0.65, 0.65-1.1, 1.1-2.1, 2.1-11, and >11 μm) and in two different phases (suspended particulate and dissolved) in rainwater were determined by inductively coupled plasma mass spectrometry (ICP-MS). Positive Eu and Tb anomalies were observed in size-classified APM. These anomalies may be due to large emissions of Eu and Tb to the atmosphere resulting from the recent change in Japan from the use of cathode-ray tubes to plasma displays in television sets (Eu and Tb) and from the widespread use of magneto-optical disks (Tb). The light REEs were enriched in fine APM particles (diameter < 1.1 μm). Because compositions of La/Ce/Sm in fine APM (diameter < 1.1 μm) were similar to those in automobile catalyst, the light REE enrichment was attributed to automobile emissions. In contrast, the REE distribution pattern in the suspended particulate phase in rainwater was similar to that in coarse APM (diameter > 2.1 μm), and a positive Tb anomaly was observed, suggesting that coarse particles easily become trapped in rain droplets. A negative Eu anomaly was observed in the dissolved phase in rainwater, but not in APM or in the suspended particulate phase in rainwater. Unlike other REEs, Eu can exist as both bivalent and trivalent ions in nature, and Eu-selective dissolution from or adsorption onto the trapped particles of Eu might account for the negative anomaly. These results show that atmospheric REE cycling is affected by the physico-chemical properties of APM.

Direct atomic-absorption determination of platinum, palladium, and rhodium in dead ceramic-based autocatalysts

The data on the effect of different concentrations of components of dead automobile catalysts on determination of platinum, palladium, and rhodium using the method of ETAAS are obtained and systematized. The conditions for direct atomic-absorption determination of Pt, Pd, and Rh are optimized. The technique of atomic-absorption determination of PM in secondary raw and technogenic materials is developed (n × 10−4−n × 10−1 wt %, sr = 0.12–0.07).

ChemInform Abstract: Thermal Stability of Catalyst Supports

Summary Thermal sintering of catalysts and supports is a major cause of irreversible catalyst deactivation. In this presentation, the mechanisms of sintering are reviewed with particular emphasis on the importance of foreign ions and of ambient atmosphere - factors of interest in the context of heterogeneous catalysis. It is shown, using the example of alumina, that controlled sintering can lead to supports that maintain desired texture for longer periods of time. Calcining in the presence of steam is shown to produce a support particularly suitable for partial oxidation catalysis. Calcining under the influence of sulphur oxides is found to produce a high temperature stable support suitable for application in car exhaust catalysts.

The characteristics of automobile catalyst-derived platinum group elements in road dusts and roadside soils: a case study in the Pearl River Delta region, South China

The emission of platinum group elements (PGE) from automobile catalytic converters has led to enrichment of PGE in road dusts and roadside soils in urban areas that are well above the natural background levels. This paper evaluates the source of contamination of all the PGE and Au in road dusts and roadside soils in the Pearl River Delta region, including three major cities, Shenzhen, Guangzhou and Hong Kong, South China. Samples were digested using Carius tube and analyzed by isotope dilution ICP-MS; Os was separated by distillation and other PGE by Te-coprecipitation. All samples have elevated PGE concentrations above the background values of uncontaminated soils and contain higher Pt, Pd and Rh than other PGE. The maximum values are 181 ng/g Pt, 514 ng/g Pd, 53 ng/g Rh and 1345 ng/g Au. There are clear positive correlations between Pt and Pd, Pt and Rh, and Pd and Rh, indicating that the main emitted of PGE from automobile catalyst are Pt, Pd and Rh. High concentrations of Au were also found in road dust samples from Hong Kong and Shenzhen. Dust samples with higher Os contents have lower 187Os/188Os ratios. Samples from Hong Kong show relatively high Pt/Rh ratios. Positive correlations between Pt and Ru, and Pt and Ir were found in Shenzhen and Hong Kong, but only positive correlations between Pt and Ir were found in Guangzhou. These different characteristics reflect different automobile catalytic systems used in Hong Kong and mainland China.

Selective recovery of catalyst layer from supporting matrix of ceramic-honeycomb-type automobile catalyst

Natural resources of platinum group metals (PGMs) are limited and their demand is increasing because of their extensive uses in industrial applications. The low rate of production of PGMs due to low concentration in the related natural ores and high cost of production have made the recovery of PGMs from previously discarded catalytic converters a viable proposition. The ceramic-honeycomb-type automobile catalytic converter contains appreciable amount of PGMs. These valuable substances, which are embedded in the catalyst layer and covered on the surface of the supporting matrix, were selectively recovered by attrition scrubbing. The attrition scrubbing was effective for the selective recovery of catalyst layer. The process was convinced as the comminution and separation process by physical impact and shearing action between particles in the scrubbing vessel. The catalyst layer was dislodged from the surface of the supporting matrix into fine particles by attrition scrubbing. The recovery of Al 2O 3 and total PGMs in the fraction less than 300 μm increased with the residence time whereas their contents in the recovered materials slightly decreased. The interparticle scrubbing became favorable when the initial input size increased. However, the solid/liquid ratio in the mixing vessel was slightly affected by the low density of converter particles.

Process for the separation and recovery of palladium and platinum from spent automobile catalyst leach liquor using LIX 84I and Alamine 336

Spent catalysts from automobile industry contain environmentally critical and economically valuable metals such as Pt, Pd, Fe, Ni, Mn, and Cr. In this paper, we present a process for the selective separation and complete recovery of palladium (Pd) and platinum (Pt) from hydrochloric acid leach liquors of spent automobile catalyst employing solvent extraction method. Typical composition of leach liquor used for the present study contains (mg/L): Pd-150, Pt-550, Mn-500, Ni-1000, Fe-1500, Cr-100 and 3 M HCl. Selective separation of Pd from the leach liquor is achieved with 0.5 vol.% LIX 84I (2-hydroxy-5-nonylacetophenone oxime in a mixture with a high flash point hydrocarbon diluent) in kerosene at an aqueous to organic (A/O) ratio of 3 in 2 stages, with an enrichment factor of three. Quantitative stripping of Pd from loaded organic is achieved with 0.5 M thiourea and 1 M HCl. Co-extraction of Fe and Pt with 5 vol.% Alamine 336 (tertiary amine of mixed tri-octyl/decyl amine) in kerosene followed by selective scrubbing of Fe with dilute HCl and complete stripping of Pt from loaded organic was proposed with 0.5 M thiourea and 0.1 M HCl. Purity of Pd and Pt strip solutions are 99.7%. Finally, the present process can solve environmental related issues and at the same time recover valuable metals in pure form.

Solvent extraction separation and recovery of palladium and platinum from chloride leach liquors of spent automobile catalyst

Spent catalysts from automobile industry contain environmentally critical and economically valuable metals such as Pt, Pd, Fe, Ni, Mn, and Cr. In this paper, we report the solvent extraction separation and recovery of palladium (Pd) and platinum (Pt) from hydrochloric acid leach liquors of spent automobile catalyst employing precipitation and solvent extraction methods. Composition of synthetic leach liquor (LL) used for the present study contains (mg/L): Pd-150, Pt-550, Mn-500, Ni-1000, Fe-1500, Cr-100 and 3 M HCl. Variation of tri- n-butyl phosphate (TBP) in the range from 0.0018 to 0.183 M in kerosene indicated selective and quantitative extraction of Pd even at the lowest extractant concentration. McCabe-Thiele plot for Pd extraction with 0.0054 M TBP predicted complete separation of metal in two stages at an aqueous to organic (A/O) phase ratio of 3.75. Counter-current batch extraction simulation (CCES) of Pd at an A/O of 3.75 resulted in a raffinate containing 0.13 mg/L of Pd, corresponding to Pd extraction efficiency of 99.9%. Stripping of Pd from loaded organic (LO) phase at O/A ratio of 5 with 0.5 M thiourea and 0.1 M HCl indicated 1.1 mg/L of Pd in spent organic (SO), with a stripping efficiency of 99.8%. The strip solution (SS) contains 2.8 g/L of Pd, with overall enrichment factor of 18.8 times. From the Pd-raffinate, complete removal of iron (Fe), 72% Cr and 5% Ni and 9.2% Mn was achieved at an aqueous pH of 3.2; whereas the loss of Pt was ∼9.1%. The observed loss of Pt was due to adsorption of metal on the hydrated iron oxide generated in situ. Variation of Aliquat 336 in the range from 0.002 to 0.22 M on the extraction of Pt from Pd-Fe free raffinate showed selective extraction of Pt and reached to 99.7% at 0.011 M concentration. McCabe-Thiele plot for Pt extraction with 0.011 M Aliquat 336 predicted >99% extraction of Pt in two stages at A/O phase ratio of 3 and two stages of stripping with 0.5 M each of thiourea and HCl at an O/A phase ratio 4. Extraction and stripping simulation tests confirmed Pt extraction and stripping efficiency of 99.83 and 99.9%, respectively with an enrichment factor of 12 times. Finally, complete flow sheet of the process for the separation and recovery of Pd and Pt as chlorides was demonstrated.

Problems, possibilities and limitations of inductively coupled plasma atomic emission spectrometry in the determination of platinum, palladium and rhodium in samples with different matrix composition

The economic and geological importance of platinum group of elements has led to the development of analytical methods to quantify them in different types of samples. In the present paper the quantitative information for spectral interference in radial viewing 40.68 MHz inductively coupled plasma atomic emission spectrometry in the determination of Pt, Pd and Rh in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti as matrix constituents was obtained. The database was used for optimum line selections. By using the selected analysis lines the following detection limits in ng g − 1 were obtained: Pt 1700, Pd-1440, Rh-900. The reached detection limits determine the possibilities and limitation of the direct ICP-AES method in the determination of Pt, Pd and Rh in geological and environmental materials. The database for spectral interferences in the presence of aluminum can be used for the determination of platinum group of elements in car catalysts. The accuracy of the analytical results was experimentally demonstrated by two certified reference materials that were analyzed: SARM 7, Pt ore and recycled auto-catalyst certified reference material SRM 2556.

Platinum Group Metal Flows of Europe, Part II

SummaryA model of the use of the platinum group metals (PGMs) platinum, palladium, and rhodium in Europe has been developed and combined with a model of the environmental pressures related to PGM production. Compared to the base case presented in Part I of this pair of articles, potential changes in PGM production and use are quantified with regard to cumulative and yearly environmental impacts and PGM resource use, for the period 2005–2020. Reducing sulfur dioxide (SO2) emissions of PGM producer Norilsk Nickel could cut the cumulative SO2 emissions associated with the use of PGMs in Europe by 35%. Cleaner electricity generation in South Africa could reduce cumulative SO2 emissions by another 9%. Increasing the recycling rate of end‐of‐life catalytic converters to 70% in 2020 could save 15% of the cumulative primary PGM input into car catalysts and 10% of the SO2 emissions associated with PGM production. In 2020, PGM requirements and SO2 emissions would be, respectively, 40% and 22% lower than the base case.Substituting palladium for part of the platinum in diesel catalysts, coupled with a probable palladium price increase, could imply 15% more cumulative SO2 emissions if recycling rates do not increase.A future large‐scale introduction of fuel cell vehicles would require technological improvements to significantly reduce the PGM content of the fuel cell stack. The basic design of such vehicles greatly influences the vehicle power, a key parameter in determining the total PGM requirement.

AlPO4 as a Support Capable of Minimizing Threshold Loading of Rh in Automotive Catalysts

Aluminum phosphate (AlPO4) was found to be an efficient and robust support material to produce optimum metal−support interactions that can reduce significantly Rh loading of automobile catalysts, owing to thermally stable and highly dispersed Rh nanoparticles anchored strongly onto the phosphate surface.

Certification of the mass fractions of Pt, Pd and Rh in a used car catalyst reference material

The high economic value of catalysts containing the platinum group elements platinum, rhodium and palladium as active components causes the need to be able to measure the precious metal loading with small uncertainty and to have suitable certified reference materials fulfilling high demands on the quality of the certified values. In European Reference Material ERM®-EB504, a used cordierite-based car catalyst material, mass fractions of platinum, palladium and rhodium were certified. The raw material was milled, homogenised and annealed before analysis. Seventeen laboratories experienced in precious metals analysis participated in the certification interlaboratory comparison, most of them analysing with inductively coupled plasma optical emission spectrometry using different sample pretreatment techniques. Homogeneity testing was carried out using X-ray fluorescence spectrometry. The certified mass fractions of Pt, Pd and Rh and their expanded uncertainties (k = 2) in ERM®-EB504 are (1777 ± 15), (279 ± 6) and (338 ± 4) mg/kg respectively.

Studies of Reaction Mechanism of Automobile Catalysts by in-situ Spectroscopy

Although IR and UV-Vis are conventionally used spectroscopies, in-situ analysis gives new and effective insights of the reaction mechanism of catalysts. In this manuscript, application of in-situ IR and UV-Vis to the reaction mechanism of automobile catalysts is described. The first topic is kinetic analysis of stored nitrates on NSR (NOx Storage-Reduction) catalyst by in-situ IR. The application of in-situ IR to the study on reaction mechanism of HC-SCR (Selective Catalytic Reduction of NO by hydrocarbons) over Ag/alumina catalyst is also reported. The effect of carbon number in hydrocarbon reductants is clarified. Finally, observation of morphology change in Ag species of Ag/alumina catalyst by in-situ UV-Vis is described. From the comparison of dynamic change in morphology of Ag species and catalytic activity, the mechanism of hydrogen effect on HC-SCR is clarified.

Concentrations of anthropogenic Pt and Pd in urban roadside soils in Xuzhou, China

The potential accumulation of platinum group elements (PGE) in the environment from automobile catalysts is high in urban areas, with the major sinks being roadside soils. Therefore, this investigation presented the detailed study on characterized concentrations of Pt and Pd and their enrichment ratios in urban roadside soils in Xuzhou, China in March 2003. Data from 21 roadside topsoil samples analyzed by inductively coupled plasma-mass spectrometer (ICP-MS) illustrated that the medians of concentrations of Pt and Pd were 2.9 and 2.8 ng/g, respectively. Hierarchical clustering analysis indicated that Pt and Pd were mainly from traffic emissions. Compared to unpolluted soils, computation of Pt and Pd enrichment ratios suggested that the Xuzhou roadside soils had average enrichment factors of 3.53 for Pt (in range of 1.22–5.73) and of 3.37 for Pd (in range of 1.35–4.46). Lower Pt/Pd ratios (in range of 0.35–2.86) in relation to similar studies in other countries were observed, which might be due to the different Pt/Pd ratios in Chinese automobile catalytic converters. Moreover, fine fraction (<250 μm) contained higher concentrations of Pt and Pd compared to the coarse fraction (250–500 μmm).

Platinum group metals bulk analysis in automobile catalyst recycling material by laser-induced breakdown spectroscopy

Development and application of an in-situ applicable method to provide rapid determination of platinum group metals (platinum, palladium, and rhodium) elemental concentration in automobile catalyst scrap is reported. Application is based on laser-induced breakdown spectroscopy (LIBS). Actual automobile catalyst slurry in powder form was used to develop the application. With a method requiring approximately 1.5 min of examination per sample, calibration curves are presented with linear regression coefficients close to 0.99 and stability better than 3.0%.

Platinum Group Metal Flows of Europe, Part 1

SummaryIn this article, we analyze flows of the platinum group metals (PGMs) platinum, palladium, and rhodium and the environmental impacts associated with their supply in Europe. A model of the use of PGMs in Europe has been developed, and this is combined with a model of environmental pressures related to PGM production.Seven industrial sectors and product groups form the main users of PGMs in Europe, comprising the chemical, petroleum, and glass industries; jewelry, dentistry, electronic equipment, and car catalysts. Most relevant environmental impacts of secondary production in Europe and primary PGM production in South Africa, Russia, and Canada are taken into account, including emissions of sulphur dioxide and carbon dioxide and total material requirement.The article quantifies the PGM flows to, from, and within Europe in 2004. The automotive industry is the single largest user of primary PGMs, and catalytic converters represent the major PGM end use. The chemical and glass industries also require large amounts of PGM but rely mostly on secondary metals. The environmental impacts of primary production exceed those of secondary production by far. An analysis of the use of car catalytic converters shows that as a result of efforts to reduce air pollutant emissions in Europe, other negative environmental impacts, such as point‐source pollution and mining waste, are occurring elsewhere—for example, at extraction and refining sites in Siberia and South Africa.

SULFUR COMPOUNDS IN MIXING DIESEL AND BIODIESEL

The mixing of biodiesel and petroleum diesel is being widely used as an attempt to reduce the emissions of sulfur compounds. These compounds are responsible for pollution, causing several diseases, like some breath problems. Sulfur compounds cause car catalyst poisoning and deactivation of processing, contributing to undesirable emissions of other toxic compounds. The goal of this work was to identify sulfur compounds in diesel and in some biodiesel mixtures of different sources. Gas chromatography system coupled with FID (flame ionization detector) was the methodology initially employed, for adjustment of the operational conditions, since FID is a low selectivity detector capable of identifying sulfur compounds and the majority of hydrocarbons. After that, a selective detector for sulfur compounds was employed (SCD - sulfur chemiluminescence detector). The results showed that sulfur compounds decreased proportionally with the addition of biodiesel.

The Environmental Impact of the Platinum Group Elements (Pt, Pd, Rh) Emitted by the Automobile Catalyst Converters

The present paper deals with an extensive review of literature concerning the platinum group elements (PGEs), and their impact on the environment. The increased number of cars and vehicles fitted with catalytic converters, has been linked with the wide spread in the environment of the PGEs, i.e. Pt, Pd and Rh. Numerous studies present compelling evidence that the catalytic converters, do not only minimize the pollution caused by the car exhaust fumes, but also they release in the environment particulate matter containing the above noble elements, which accumulate in the soil, and plants, or remain suspended in the air, being transported to large distances. Indeed, the concentration of these noble elements in the soil and plants has increased significantly during the last 10–15 years, especially along the road side of high ways. Assessment of the PGEs health risk was originally based on measuring the body fluid in Pt, Pd and Rh content of occupationally involved people, as well as of the general population. Recent results based on cellular studies show that the PGEs are related to respiratory sensitization, allergic reactions, dermatitis, urticaria, damage of the epithelial lung cells, asthma, rhinoconjuctivitis, lymphocyte proliferation and cytokine release and possibly to cancer. In spite of the progress attained, more work is necessary for an accurate health risk assessment.